The present invention generally relates to video signal transmission systems, and in particular to a video signal transmission system for transmitting a video signal using a band compression technique.
Various transmission systems are proposed for transmission of a video signal via various signal transmission media including magnetic recording medium, by converting the video signal into a predetermined signal format. The ultimate objective of such video signal transmission systems is to achieve a high resolution video transmission and processing.
Recent progress in digital memories supported by the progress in design and manufacturing technique of integrated circuits have made it possible to construct digital memories with low costs. Using such digital memories, improvement in the picture quality of the various video apparatus has been attempted.
For example, the picture quality of television is improved by a video processing using digital memories. Also, there is a so called non-interlace television system which apparently improves the resolution of the picture in the vertical direction by performing a non-interlace processing. In this processing, the digital memories are used for intrafield, interfield, or interframe processing.
The picture quality is also improved in the magnetic recording and reproducing apparatuses such as a video tape recorder by using digital field memories. The digital field memory is used, for example, for a noise reduction circuit which eliminates the noise from the picture by utilizing the field correlation of the video signal.
However, such a television or video tape recorder using the digital memories are generally still insufficient in achieving the desired picture quality. In the case of the video tape recorder using noise reduction circuit, in particular, the improvement in the picture quality is attempted only by elimination of the noise from the picture. In this way, substantial improvement in the actual resolution cannot be not obtained.
On the other hand, there is a so called "High Definition Television System" proposed by the Nippon Hoso Kyokai (NHK) which substantially improves the resolution and picture quality. Further, there is proposed a high resolution video tape recorder in which the design of the magnetic head and the circuit is also changed. In combination with a high performance magnetic tape, such a high resolution video tape recorder achieves the recording and reproduction of frequency modulated luminance signal which has a higher carrier frequency and a larger bandwidth as compared with those for the conventional video tape recorder. Such a high resolution video tape recorder indeed provides a reproduced picture having a substantially improved resolution. Unfortunately, such a high resolution video tape recorder is not compatible with the conventional home video tape recorder which is commonly used. The magnetic tape for use in such a high resolution video tape recorder is also not compatible with the conventional apparatus. Similarly, the aforementioned High Definition Television System is not compatible with the current video signal transmission system such as the NTSC system according to which the current television receivers are designed.